Open Access
Multifunctional properties of a bacillus thuringiensis strain (BST-122): beyond the parasporal crystal
(MDPI, 2022) Unzue Pozas, Argiñe; Caballero, Carlos J.; Villanueva, Maite; Fernández González, Ana Beatriz; Caballero Murillo, Primitivo; Institute for Multidisciplinary Research in Applied Biology - IMAB
Chemical products still represent the most common form of controlling crop pests and diseases. However, their extensive use has led to the selection of resistances. This makes the finding of new solutions paramount to countering the economic losses that pests and diseases represent in modern agriculture. Bacillus thuringiensis (Bt) is one of the most reliable alternatives to chemical-based solutions. In this study, we aimed to further expand the global applicability of Bt strains beyond their spores and crystals. To this end, we selected a new Bt strain (BST-122) with relevant toxicity factors and tested its activity against species belonging to different phyla. The spore and crystal mixture showed toxicity to coleopterans. Additionally, a novel Cry5-like protein proved active against the two-spotted spider mite. In vivo and plant assays revealed significant control of the parasitic nematode, Meloidogyne incognita. Surprisingly, our data indicated that the nematocidal determinants may be secreted. When evaluated against phytopathogenic fungi, the strain seemed to decelerate their growth. Overall, our research has highlighted the potential of Bt strains, expanding their use beyond the confinements of spores and crystals. However, further studies are required to pinpoint the factors responsible for the wide host range properties of the BST-122 strain.
Open Access
A strain of Bacillus thuringiensis containing a novel cry7Aa2 gene that is toxic to Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae)
(MDPI, 2019) Domínguez Arrizabalaga, Mikel; Villanueva San Martín, Maite; Fernández González, Ana Beatriz; Caballero Murillo, Primitivo; Institute for Multidisciplinary Research in Applied Biology - IMAB; Gobierno de Navarra / Nafarroako Gobernua
The genome of the Bacillus thuringiensis BM311.1 strain was sequenced and assembled in 359 contigs containing a total of 6,390,221 bp. The plasmidic ORF of a putative cry gene from this strain was identified as a potential novel Cry protein of 1138 amino acid residues with a 98% identity compared to Cry7Aa1 and a predicted molecular mass of 129.4 kDa. The primary structure of Cry7Aa2, which had eight conserved blocks and the classical structure of three domains, differed in 28 amino acid residues from that of Cry7Aa1. The cry7Aa2 gene was amplified by PCR and then expressed in the acrystalliferous strain BMB171. SDS-PAGE analysis confirmed the predicted molecular mass for the Cry7Aa2 protein and revealed that after in vitro trypsin incubation, the protein was degraded to a toxin of 62 kDa. However, when treated with digestive fluids from Leptinotarsa decemlineata larvae, one major proteinase-resistant fragment of slightly smaller size was produced. The spore and crystal mixture produced by the wild-type BM311.1 strain against L. decemlineata neonate larvae resulted in a LC50 value of 18.8 mu g/mL, which was statistically similar to the estimated LC50 of 20.8 mu g/mL for the recombinant BMB17-Cry7Aa2 strain. In addition, when this novel toxin was activated in vitro with commercial trypsin, the LC50 value was reduced 3.8-fold to LC50 = 4.9 mu g/mL. The potential advantages of Cry7Aa2 protoxin compared to Cry7Aa1 protoxin when used in the control of insect pests are discussed.
Open Access
Bacillus thuringiensis Cyt proteins as enablers of activity of Cry and Tpp toxins against Aedes albopictus
(2023) Lai, Liliana; Villanueva, Maite; Muruzabal Galarza, Ane; Fernández González, Ana Beatriz; Unzue Pozas, Argiñe; Toledo Arana, Alejandro; Caballero Murillo, Primitivo; Caballero Sánchez, Carlos; Institute for Multidisciplinary Research in Applied Biology - IMAB
Aedes albopictus is a species of mosquito, originally from Southeast Asia, that belongs to the Culicidae family and the Dipteran insect order. The distribution of this vector has rapidly changed over the past decade, making most of the temperate territories in the world vulnerable to important human vector-borne diseases such as dengue, yellow fever, zika or chikungunya. Bacillus thuringiensis var. israeliensis (Bti)-based insecticides represent a realistic alternative to the most common synthetic insecticides for the control of mosquito larvae. However, several studies have revealed emerging resistances to the major Bti Crystal proteins such as Cry4Aa, Cry4Ba and Cry11Aa, making the finding of new toxins necessary to diminish the exposure to the same toxicity factors overtime. Here, we characterized the individual activity of Cyt1Aa, Cry4Aa, Cry4Ba and Cry11Aa against A. albopictus and found a new protein, Cyt1A-like, that increases the activity of Cry11Aa more than 20-fold. Additionally, we demonstrated that Cyt1A-like facilitates the activity three new Bti toxins: Cry53-like, Cry56A-like and Tpp36-like. All in all, these results provide alternatives to the currently available Bti products for the control of mosquito populations and position Cyt proteins as enablers of activity for otherwise non-active crystal proteins.

Fernández González, Ana Beatriz

Email Address

person.page.identifierURI

Birth Date

Job Title

Last Name

First Name

person.page.departamento

person.page.instituteName

ORCID

person.page.observainves

person.page.upna

Name

Filters

Author

Subject

Date

Has files

Item Type

Type

Settings

Sort By

Results per page

Search Results